1. Field of the Invention
The present invention relates to a control system/method for controlling range shifting in a compound transmission having a lever-shifted main section and a range section shifted by a range section actuator for selectively positioning a synchronized double-acting positive clutch. The transmission may also have a splitter section. In particular, the present invention relates to controlling range shifting in a lever-shifted, partially automated vehicular transmission system having a microprocessor-based controller for controlling the operation of a range shift actuator and/or an engine fuel control.
2. Description of the Related Art
Controller-assisted, manually shifted transmission systems are known in the prior art, as may be seen by reference to U.S. Pat. Nos. 5,582,558; 5,755,639; 5,766,111; 5,791,189; 5,974,906; 5,989,155 and 6,015,366, the disclosures of which are incorporated herein by reference.
Compound transmissions having a range and/or combined range- and splitter-type auxiliary transmission section are well known in the prior art, as may be seen by reference to U.S. Pat. Nos. 4,754,665 and 5,390,561, the disclosures of which are incorporated herein by reference.
Transmissions having manually shifted main sections and automatically shifted splitter sections are known in the prior art, as may be seen by reference to U.S. Pat. Nos. 5,435,212; 5,938,711; 6,007,455 and 6,044,721, the disclosures of which are incorporated herein by reference.
Compound transmissions having automatically implemented range shifting are well known in the prior art, as may be seen by reference to U.S. Pat. Nos. 5,911,787 and 5,974,906, the disclosures of which are incorporated herein by reference.
Drivers have been known to operate their vehicles with a main section of the transmission in neutral on downhill grades for an extended period of time.
In an exemplary range section, the high speed range to low speed range step is approximately 3½ to one. That is, when a range shift is executed from low to high, the speed of the high speed gear must be decreased by a factor of 3½ to enable synchronization. At relatively low speeds, this is achieved without significant difficult. However, at relatively high speeds, as might be experienced on highways, the energy needed to decelerate the high speed gear and the rotatably connected auxiliary unit countershafts and gears rotating therewith to synchronous speed is quite considerable. Attempting to synchronize the speeds at elevated road speeds has been identified as a source of damage to the high speed range synchronizers.